00:01
So in this problem, we're going to be expanding this binomial out to its full form.
00:06
So we have x minus y to the seventh.
00:09
And we know that our formula kind of works with this a plus b to the nth.
00:13
So we want an a plus b form.
00:16
So instead of doing minus y, we would do x plus negative y.
00:22
And that way we can have a b term that is easier to work with.
00:26
So the best thing to do here is work with what our n is.
00:31
So here n is this number that we're raising the whole whatever is in the parentheses to and it happens to be 7.
00:38
So we take the line where 7th is the 7 is the second term.
00:42
That's the second to last line.
00:47
So now that we have that, we can go and kind of start expanding.
00:52
And so what we would do is we start with a to the 7th and count down by 1 for each time.
00:57
Term that we have.
00:59
And then we start with b to the 0th and we count up by each term we add.
01:03
And we leave the coefficients in there at the beginning.
01:06
So this first term has a coefficient 1 and that's times the a term which is x to the 7th...